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Antibiotics
An antibiotic is a type of substance active against and is the most important type of for fighting . Antibiotic s are widely used in the and of such infections. They may either or of . A limited number of antibiotics also possess activity. Antibiotics are not effective against es such as the or ; drugs which inhibit viruses are termed s or antivirals rather than antibiotics. Sometimes, the term antibiotic which means "opposing life", based on roots, (??t?-) anti: "against" and (ß???-) biotic: "life", is broadly used to refer to any substance used against s, but in the usual medical usage, antibiotics (such as ) are those produced naturally (by one fighting another), whereas nonantibiotic antibacterials (such as s and s) are . However, both classes have the same goal of killing or preventing the growth of microorganisms, and both are included in . "Antibacterials" include drugs, s, and chemical s, whereas antibiotics are an important class of antibacterials used more specifically in medicine and . Antibiotics have been used since ancient times. Many civilizations used topical application of mouldy bread, with many references to its beneficial effects arising from ancient Egypt, China, Serbia, Greece and Rome. The first person to directly document the use of moulds to treat infections was John Parkinson (1567–1650). Antibiotics revolutionized medicine in the 20th century. (1881–1955) discovered modern day in 1928. After realizing the great potential there was in penicillin, Fleming pursued the challenge of how to market it and translate it to commercial use. With help from other biochemists, penicillin was finally available for widespread use. This was significantly beneficial during wartime. Unfortunately, it didn't take long for resistance to begin. Effectiveness and easy access have also led to their and some bacteria have developed . This has led to widespread problems, and the has classified antimicrobial resistance as a "serious threat that is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country". Medical uses Antibiotics are used to treat or prevent bacterial infections, and sometimes s. ( is effective against a number of s). When an infection is suspected of being responsible for an illness but the responsible pathogen has not been identified, an is adopted. This involves the administration of a based on the signs and symptoms presented and is initiated pending laboratory results that can take several days. When the responsible pathogenic microorganism is already known or has been identified, can be started. This will usually involve the use of a narrow-spectrum antibiotic. The choice of antibiotic given will also be based on its cost. Identification is critically important as it can reduce the cost and toxicity of the antibiotic therapy and also reduce the possibility of the emergence of antimicrobial resistance. To avoid surgery, antibiotics may be given for non-complicated acute . Antibiotics may be given as a and this is usually limited to at-risk populations such as those with a (particularly in cases to prevent ), those taking s, patients, and those having . Their use in surgical procedures is to help prevent infection of . They have an important role in where their use may prevent and consequent . Antibiotics are also used to prevent infection in cases of particularly cancer-related. Administration There are many different for antibiotic treatment. Antibiotics are usually . In more severe cases, particularly deep-seated , antibiotics can be given or by injection. Where the site of infection is easily accessed, antibiotics may be given in the form of s onto the for or s for ear infections and acute cases of . Topical use is also one of the treatment options for some skin conditions including and . Advantages of topical application include achieving high and sustained concentration of antibiotic at the site of infection; reducing the potential for systemic absorption and toxicity, and total volumes of antibiotic required are reduced, thereby also reducing the risk of antibiotic misuse. Topical antibiotics applied over certain types of surgical wounds have been reported to reduce the risk of surgical site infections. However, there are certain general causes for concern with topical administration of antibiotics. Some systemic absorption of the antibiotic may occur; the quantity of antibiotic applied is difficult to accurately dose, and there is also the possibility of local reactions or occurring. Prevalence Antibiotic consumption varies widely between countries. The ‘ report on surveillance of antibiotic consumption’ published in 2018 analysed 2015 data from 65 countries. As measured in defined daily doses per 1,000 inhabitants per day. Mongolia had the highest consumption with a rate of 64.4. Burundi had the lowest at 4.4. and were the most frequently consumed. Side effects Antibiotics are screened for any negative effects before their approval for clinical use, and are usually considered safe and well tolerated. However, some antibiotics have been associated with a wide extent of adverse s ranging from mild to very severe depending on the type of antibiotic used, the microbes targeted, and the individual patient. Side effects may reflect the pharmacological or toxicological properties of the antibiotic or may involve hypersensitivity or reactions. Adverse effects range from fever and nausea to major allergic reactions, including and . Safety profiles of newer drugs are often not as well established as for those that have a long history of use. Common side-effects include , resulting from disruption of the species composition in the , resulting, for example, in overgrowth of pathogenic bacteria, such as . Antibacterials can also affect the , and may lead to overgrowth of species of the genus in the vulvo-vaginal area. Additional side effects can result from with other drugs, such as the possibility of damage from the administration of a with a systemic . Correlation with obesity Exposure to antibiotics early in life is associated with increased body mass in humans and mouse models. Early life is a critical period for the establishment of the and for development. Mice exposed to subtherapeutic antibiotic treatment (STAT)– with either penicillin, , or had altered composition of the gut microbiota as well as its metabolic capabilities. One study has reported that mice given low-dose penicillin (1 µg/g body weight) around birth and throughout the process had an increased body mass and fat mass, accelerated growth, and increased expression of s involved in , compared to control mice. In addition, penicillin in combination with a high-fat diet increased fasting levels in mice. However, it is unclear whether or not antibiotics cause in humans. Studies have found a correlation between early exposure of antibiotics (<6 months) and increased body mass (at 10 and 20 months). Another study found that the type of antibiotic exposure was also significant with the highest risk of being overweight in those given s compared to penicillin and . Therefore, there is correlation between antibiotic exposure in early life and obesity in humans, but whether or not there is a causal relationship remains unclear. Although there is a correlation between antibiotic use in early life and obesity, the effect of antibiotics on obesity in humans needs to be weighed against the beneficial effects of clinically indicated treatment with antibiotics in infancy. Interactions Birth control pills There are few well-controlled studies on whether antibiotic use increases the risk of failure. The majority of studies indicate antibiotics do not interfere with , such as clinical studies that suggest the failure rate of contraceptive pills caused by antibiotics is very low (about 1%). Situations that may increase the risk of oral contraceptive failure include (missing taking the pill), vomiting, or diarrhea. Gastrointestinal disorders or interpatient variability in oral contraceptive absorption affecting in the blood. Women with may be at higher risk of failure and should be advised to use during antibiotic treatment and for one week after its completion. If patient-specific risk factors for reduced oral contraceptive efficacy are suspected, backup contraception is recommended. In cases where antibiotics have been suggested to affect the efficiency of birth control pills, such as for the broad-spectrum antibiotic , these cases may be due to an increase in the activities of hepatic liver enzymes' causing increased breakdown of the pill's active ingredients. Effects on the , which might result in reduced absorption of s in the colon, have also been suggested, but such suggestions have been inconclusive and controversial. Clinicians have recommended that extra contraceptive measures be applied during therapies using antibiotics that are suspected to interact with oral s. More studies on the possible interactions between antibiotics and birth control pills (oral contraceptives) are required as well as careful assessment of patient-specific risk factors for potential oral contractive pill failure prior to dismissing the need for backup contraception. Alcohol Interactions between alcohol and certain antibiotics may occur and may cause side effects and decreased effectiveness of antibiotic therapy. While moderate alcohol consumption is unlikely to interfere with many common antibiotics, there are specific types of antibiotics, with which alcohol consumption may cause serious side effects. Therefore, potential risks of side effects and effectiveness depend on the type of antibiotic administered. Antibiotics such as , , , , , , and , cause a -like chemical reaction with alcohol by inhibiting its breakdown by , which may result in vomiting, nausea, and shortness of breath. In addition, the efficacy of doxycycline and succinate may be reduced by alcohol consumption. Other effects of alcohol on antibiotic activity include altered activity of the liver enzymes that break down the antibiotic compound. Classes Antibiotics are commonly classified based on their , , or spectrum of activity. Most target bacterial functions or growth processes. Those that target the bacterial cell wall ( s and s) or the cell membrane ( s), or interfere with essential bacterial enzymes ( s, s, , and ) have activities. s ( s, , and s) are usually (with the exception of bactericidal s). Further categorization is based on their target specificity. "Narrow-spectrum" antibiotics target specific types of bacteria, such as or , whereas affect a wide range of bacteria. Following a 40-year break in discovering new classes of antibacterial compounds, four new classes of antibiotics have been brought into clinical use in the late 2000s and early 2010s: cyclic s (such as ), (such as ), s (such as ), and s (such as ). Resistance of a human ingesting (MRSA)}} The emergence of resistance of bacteria to antibiotics is a common phenomenon. Emergence of resistance often reflects ary processes that take place during antibiotic therapy. The antibiotic treatment may for bacterial strains with physiologically or genetically enhanced capacity to survive high doses of antibiotics. Under certain conditions, it may result in preferential growth of resistant bacteria, while growth of susceptible bacteria is inhibited by the drug. For example, antibacterial selection for strains having previously acquired antibacterial-resistance genes was demonstrated in 1943 by the . Antibiotics such as penicillin and erythromycin, which used to have a high efficacy against many bacterial species and strains, have become less effective, due to the increased resistance of many bacterial strains. Resistance may take the form of biodegredation of pharmaceuticals, such as sulfamethazine-degrading soil bacteria introduced to sulfamethazine through medicated pig feces. The survival of bacteria often results from an inheritable resistance, but the growth of resistance to antibacterials also occurs through . Horizontal transfer is more likely to happen in locations of frequent antibiotic use. Antibacterial resistance may impose a biological cost, thereby reducing of resistant strains, which can limit the spread of antibacterial-resistant bacteria, for example, in the absence of antibacterial compounds. Additional mutations, however, may compensate for this fitness cost and can aid the survival of these bacteria. Paleontological data show that both antibiotics and antibiotic resistance are ancient compounds and mechanisms. Useful antibiotic targets are those for which mutations negatively impact bacterial reproduction or viability. Several molecular mechanisms of antibacterial resistance exist. Intrinsic antibacterial resistance may be part of the genetic makeup of bacterial strains. For example, an antibiotic target may be absent from the bacterial . Acquired resistance results from a mutation in the bacterial chromosome or the acquisition of extra-chromosomal DNA. Antibacterial-producing bacteria have evolved resistance mechanisms that have been shown to be similar to, and may have been transferred to, antibacterial-resistant strains. The spread of antibacterial resistance often occurs through vertical transmission of mutations during growth and by genetic recombination of DNA by . For instance, antibacterial resistance genes can be exchanged between different bacterial strains or species via that carry these resistance genes. Plasmids that carry several different resistance genes can confer resistance to multiple antibacterials. Cross-resistance to several antibacterials may also occur when a resistance mechanism encoded by a single gene conveys resistance to more than one antibacterial compound. Antibacterial-resistant strains and species, sometimes referred to as "superbugs", now contribute to the emergence of diseases that were for a while well controlled. For example, emergent bacterial strains causing tuberculosis that are resistant to previously effective antibacterial treatments pose many therapeutic challenges. Every year, nearly half a million new cases of (MDR-TB) are estimated to occur worldwide. For example, is a newly identified enzyme conveying bacterial resistance to a broad range of antibacterials. The United Kingdom's has stated that "most isolates with NDM-1 enzyme are resistant to all standard intravenous antibiotics for treatment of severe infections." On 26 May 2016 an " " was identified in the resistant to , . Misuse Per The ICU Book "The first rule of antibiotics is try not to use them, and the second rule is try not to use too many of them." Inappropriate antibiotic treatment and overuse of antibiotics have contributed to the emergence of antibiotic-resistant bacteria. of antibiotics is an example of misuse. Many antibiotics are frequently prescribed to treat symptoms or diseases that do not respond to antibiotics or that are likely to resolve without treatment. Also, incorrect or suboptimal antibiotics are prescribed for certain bacterial infections. The overuse of antibiotics, like penicillin and erythromycin, has been associated with emerging antibiotic resistance since the 1950s. Widespread usage of antibiotics in hospitals has also been associated with increases in bacterial strains and species that no longer respond to treatment with the most common antibiotics. Common forms of antibiotic misuse include excessive use of antibiotics in travelers and failure of medical professionals to prescribe the correct dosage of antibiotics on the basis of the patient's weight and history of prior use. Other forms of misuse include failure to take the entire prescribed course of the antibiotic, incorrect dosage and administration, or failure to rest for sufficient recovery. Inappropriate antibiotic treatment, for example, is their prescription to treat viral infections such as the . One study on s found "physicians were more likely to prescribe antibiotics to patients who appeared to expect them". Multifactorial interventions aimed at both physicians and patients can reduce inappropriate prescription of antibiotics. Several organizations concerned with antimicrobial resistance are lobbying to eliminate the unnecessary use of antibiotics. The issues of misuse and overuse of antibiotics have been addressed by the formation of the US Interagency Task Force on Antimicrobial Resistance. This task force aims to actively address antimicrobial resistance, and is coordinated by the US , the (FDA), and the (NIH), as well as other US agencies. An NGO campaign group is Keep Antibiotics Working. In France, an "Antibiotics are not automatic" government campaign started in 2002 and led to a marked reduction of unnecessary antibiotic prescriptions, especially in children. The emergence of antibiotic resistance has prompted restrictions on their use in the UK in 1970 (Swann report 1969), and the EU has banned the use of antibiotics as growth-promotional agents since 2003. Moreover, several organizations (including the World Health Organization, the , and the ) have advocated restricting the amount of antibiotic use in food animal production. However, commonly there are delays in regulatory and legislative actions to limit the use of antibiotics, attributable partly to resistance against such regulation by industries using or selling antibiotics, and to the time required for research to test causal links between their use and resistance to them. Two federal bills (S.742 and H.R. 2562) aimed at phasing out nontherapeutic use of antibiotics in US food animals were proposed, but have not passed. These bills were endorsed by public health and medical organizations, including the American Holistic Nurses' Association, the American Medical Association, and the American Public Health Association (APHA). Despite pledges by food companies and restaurants to reduce or eliminate meat that comes from animals treated with antibiotics, the purchase of antibiotics for use on farm animals has been increasing every year. There has been extensive use of antibiotics in animal husbandry. In the United States, the question of emergence of antibiotic-resistant bacterial strains due to was raised by the US (FDA) in 1977. In March 2012, the United States District Court for the Southern District of New York, ruling in an action brought by the and others, ordered the FDA to revoke approvals for the use of antibiotics in livestock, which violated FDA regulations. References Category:Medical